refactor systemd D-Bus client: add caching, reconnection, and proper error propagation

containers/registry.go

@@ -548,9 +548,10 @@ func calcId(cg *cgroup.Cgroup, md *ContainerMetadata) ContainerID {
 func getContainerMetadata(cg *cgroup.Cgroup) (*ContainerMetadata, error) {
 	switch cg.ContainerType {
 	case cgroup.ContainerTypeSystemdService:
+		var err error
 		md := &ContainerMetadata{}
-		md.systemd = getSystemdProperties(cg.Id)
-		return md, nil
+		md.systemd, err = getSystemdProperties(cg.Id)
+		return md, err
 	case cgroup.ContainerTypeDocker, cgroup.ContainerTypeContainerd, cgroup.ContainerTypeSandbox, cgroup.ContainerTypeCrio:
 	default:
 		return &ContainerMetadata{}, nil

containers/systemd.go

@@ -2,6 +2,7 @@ package containers
 
 import (
 	"context"
+	"fmt"
 	"os"
 	"strconv"
 	"strings"
@@ -11,13 +12,11 @@ import (
 
 	"github.com/coreos/go-systemd/v22/dbus"
 	gdbus "github.com/godbus/dbus/v5"
-
-	"k8s.io/klog/v2"
 )
 
 var (
-	dbusConn    *dbus.Conn
 	dbusTimeout = time.Second
+	dbusClient  = NewDbusClient()
 
 	systemServicePrefixes = []string{
 		"systemd-",
@@ -37,22 +36,63 @@ var (
 	}
 )
 
-func init() {
+type DbusClient struct {
+	conn  *dbus.Conn
+	cache map[string]map[string]any
+}
+
+func NewDbusClient() *DbusClient {
+	return &DbusClient{
+		cache: map[string]map[string]any{},
+	}
+}
+
+func (c *DbusClient) close() {
+	if c.conn != nil {
+		c.conn.Close()
+		c.conn = nil
+	}
+}
+
+func (c *DbusClient) connect() error {
 	var err error
-	dbusConn, err = dbus.NewConnection(func() (*gdbus.Conn, error) {
-		c, err := gdbus.Dial("unix:path=" + proc.HostPath("/run/systemd/private"))
+	c.conn, err = dbus.NewConnection(func() (*gdbus.Conn, error) {
+		conn, err := gdbus.Dial("unix:path=" + proc.HostPath("/run/systemd/private"))
 		if err != nil {
 			return nil, err
 		}
 		methods := []gdbus.Auth{gdbus.AuthExternal(strconv.Itoa(os.Getuid()))}
-		if err = c.Auth(methods); err != nil {
-			dbusConn.Close()
+		if err = conn.Auth(methods); err != nil {
+			conn.Close()
 			return nil, err
 		}
-		return c, nil
+		return conn, nil
 	})
 	if err != nil {
-		klog.Warningln("failed to connect to systemd bus:", err)
+		return fmt.Errorf("failed to connect to systemd bus: %w", err)
+	}
+	return nil
+}
+
+func (c *DbusClient) GetAllPropertiesContext(ctx context.Context, unit string, retry bool) (map[string]any, error) {
+	if res, ok := c.cache[unit]; ok {
+		return res, nil
+	}
+	if c.conn == nil {
+		if err := c.connect(); err != nil {
+			return nil, err
+		}
+	}
+	res, err := c.conn.GetAllPropertiesContext(ctx, unit)
+	switch {
+	case err == nil:
+		c.cache[unit] = res
+		return res, nil
+	case retry:
+		c.close()
+		return c.GetAllPropertiesContext(ctx, unit, false)
+	default:
+		return nil, err
 	}
 }
 
@@ -82,11 +122,8 @@ func (sp SystemdProperties) IsSystemService() bool {
 	return false
 }
 
-func getSystemdProperties(id string) SystemdProperties {
+func getSystemdProperties(id string) (SystemdProperties, error) {
 	props := SystemdProperties{}
-	if dbusConn == nil {
-		return props
-	}
 	ctx, cancel := context.WithTimeout(context.Background(), dbusTimeout)
 	defer cancel()
 	parts := strings.Split(id, "/")
@@ -99,10 +136,9 @@ func getSystemdProperties(id string) SystemdProperties {
 	if props.Unit == "" {
 		props.Unit = parts[len(parts)-1]
 	}
-	properties, err := dbusConn.GetAllPropertiesContext(ctx, props.Unit)
+	properties, err := dbusClient.GetAllPropertiesContext(ctx, props.Unit, true)
 	if err != nil {
-		klog.Warningln("failed to get systemd properties:", err)
-		return props
+		return props, fmt.Errorf("failed to get systemd properties: %w", err)
 	}
 	if v, ok := properties["TriggeredBy"]; ok {
 		if values, _ := v.([]string); len(values) > 0 {
@@ -112,5 +148,5 @@ func getSystemdProperties(id string) SystemdProperties {
 	if v, ok := properties["Type"]; ok {
 		props.Type, _ = v.(string)
 	}
-	return props
+	return props, nil
 }

go.mod

@@ -10,13 +10,13 @@ require (
 	github.com/cilium/ebpf v0.20.0
 	github.com/containerd/cgroups v1.1.0
 	github.com/containerd/containerd v1.7.29
-	github.com/coreos/go-systemd/v22 v22.5.0
+	github.com/coreos/go-systemd/v22 v22.7.0
 	github.com/coroot/logparser v1.2.1
 	github.com/docker/docker v27.4.0+incompatible
 	github.com/florianl/go-conntrack v0.3.0
 	github.com/go-kit/log v0.2.1
 	github.com/gobwas/glob v0.2.3
-	github.com/godbus/dbus/v5 v5.1.0
+	github.com/godbus/dbus/v5 v5.2.2
 	github.com/golang/snappy v0.0.4
 	github.com/grafana/pyroscope/ebpf v0.4.9
 	github.com/jpillora/backoff v1.0.0
@@ -40,7 +40,7 @@ require (
 	golang.org/x/arch v0.4.0
 	golang.org/x/exp v0.0.0-20240808152545-0cdaa3abc0fa
 	golang.org/x/net v0.46.0
-	golang.org/x/sys v0.37.0
+	golang.org/x/sys v0.40.0
 	golang.org/x/time v0.12.0
 	gopkg.in/alecthomas/kingpin.v2 v2.2.6
 	gopkg.in/yaml.v2 v2.4.0

go.sum

@@ -82,8 +82,8 @@ github.com/containerd/typeurl/v2 v2.1.1 h1:3Q4Pt7i8nYwy2KmQWIw2+1hTvwTE/6w9Fqctt
 github.com/containerd/typeurl/v2 v2.1.1/go.mod h1:IDp2JFvbwZ31H8dQbEIY7sDl2L3o3HZj1hsSQlywkQ0=
 github.com/coreos/go-semver v0.3.1 h1:yi21YpKnrx1gt5R+la8n5WgS0kCrsPp33dmEyHReZr4=
 github.com/coreos/go-semver v0.3.1/go.mod h1:irMmmIw/7yzSRPWryHsK7EYSg09caPQL03VsM8rvUec=
-github.com/coreos/go-systemd/v22 v22.5.0 h1:RrqgGjYQKalulkV8NGVIfkXQf6YYmOyiJKk8iXXhfZs=
-github.com/coreos/go-systemd/v22 v22.5.0/go.mod h1:Y58oyj3AT4RCenI/lSvhwexgC+NSVTIJ3seZv2GcEnc=
+github.com/coreos/go-systemd/v22 v22.7.0 h1:LAEzFkke61DFROc7zNLX/WA2i5J8gYqe0rSj9KI28KA=
+github.com/coreos/go-systemd/v22 v22.7.0/go.mod h1:xNUYtjHu2EDXbsxz1i41wouACIwT7Ybq9o0BQhMwD0w=
 github.com/coroot/dotnetdiag v1.2.2 h1:PVP/By8o+xhPjfVolJYcjHLbFQInM7pkaD6/otPLc8Q=
 github.com/coroot/dotnetdiag v1.2.2/go.mod h1:veXCMlFzm1yNl7wwJb/ZLxO4WbzhDBoy1VG1XtkH2ls=
 github.com/coroot/logparser v1.2.1 h1:NLU4VAgGwqMTtKyRHDpTtE9BtPQJLOhDIuB5yiQdelQ=
@@ -172,9 +172,8 @@ github.com/go-task/slim-sprig/v3 v3.0.0 h1:sUs3vkvUymDpBKi3qH1YSqBQk9+9D/8M2mN1v
 github.com/go-task/slim-sprig/v3 v3.0.0/go.mod h1:W848ghGpv3Qj3dhTPRyJypKRiqCdHZiAzKg9hl15HA8=
 github.com/gobwas/glob v0.2.3 h1:A4xDbljILXROh+kObIiy5kIaPYD8e96x1tgBhUI5J+Y=
 github.com/gobwas/glob v0.2.3/go.mod h1:d3Ez4x06l9bZtSvzIay5+Yzi0fmZzPgnTbPcKjJAkT8=
-github.com/godbus/dbus/v5 v5.0.4/go.mod h1:xhWf0FNVPg57R7Z0UbKHbJfkEywrmjJnf7w5xrFpKfA=
-github.com/godbus/dbus/v5 v5.1.0 h1:4KLkAxT3aOY8Li4FRJe/KvhoNFFxo0m6fNuFUO8QJUk=
-github.com/godbus/dbus/v5 v5.1.0/go.mod h1:xhWf0FNVPg57R7Z0UbKHbJfkEywrmjJnf7w5xrFpKfA=
+github.com/godbus/dbus/v5 v5.2.2 h1:TUR3TgtSVDmjiXOgAAyaZbYmIeP3DPkld3jgKGV8mXQ=
+github.com/godbus/dbus/v5 v5.2.2/go.mod h1:3AAv2+hPq5rdnr5txxxRwiGjPXamgoIHgz9FPBfOp3c=
 github.com/gogo/protobuf v1.3.2 h1:Ov1cvc58UF3b5XjBnZv7+opcTcQFZebYjWzi34vdm4Q=
 github.com/gogo/protobuf v1.3.2/go.mod h1:P1XiOD3dCwIKUDQYPy72D8LYyHL2YPYrpS2s69NZV8Q=
 github.com/golang/glog v0.0.0-20160126235308-23def4e6c14b/go.mod h1:SBH7ygxi8pfUlaOkMMuAQtPIUF8ecWP5IEl/CR7VP2Q=
@@ -536,8 +535,8 @@ golang.org/x/sys v0.0.0-20220520151302-bc2c85ada10a/go.mod h1:oPkhp1MJrh7nUepCBc
 golang.org/x/sys v0.0.0-20220715151400-c0bba94af5f8/go.mod h1:oPkhp1MJrh7nUepCBck5+mAzfO9JrbApNNgaTdGDITg=
 golang.org/x/sys v0.2.0/go.mod h1:oPkhp1MJrh7nUepCBck5+mAzfO9JrbApNNgaTdGDITg=
 golang.org/x/sys v0.10.0/go.mod h1:oPkhp1MJrh7nUepCBck5+mAzfO9JrbApNNgaTdGDITg=
-golang.org/x/sys v0.37.0 h1:fdNQudmxPjkdUTPnLn5mdQv7Zwvbvpaxqs831goi9kQ=
-golang.org/x/sys v0.37.0/go.mod h1:OgkHotnGiDImocRcuBABYBEXf8A9a87e/uXjp9XT3ks=
+golang.org/x/sys v0.40.0 h1:DBZZqJ2Rkml6QMQsZywtnjnnGvHza6BTfYFWY9kjEWQ=
+golang.org/x/sys v0.40.0/go.mod h1:OgkHotnGiDImocRcuBABYBEXf8A9a87e/uXjp9XT3ks=
 golang.org/x/term v0.0.0-20201126162022-7de9c90e9dd1/go.mod h1:bj7SfCRtBDWHUb9snDiAeCFNEtKQo2Wmx5Cou7ajbmo=
 golang.org/x/term v0.36.0 h1:zMPR+aF8gfksFprF/Nc/rd1wRS1EI6nDBGyWAvDzx2Q=
 golang.org/x/term v0.36.0/go.mod h1:Qu394IJq6V6dCBRgwqshf3mPF85AqzYEzofzRdZkWss=